Frank Clark embarked from New Zealand twice. On 11 August 1914 he departed with the Samoa Advance Party, which took over the control of Samoa on August 29. After returning to New Zealand he had two days reprieve before embarking for Suez. After arriving in Suez on the 25 May Frank Clark travelled to the Dardanelles where he joined the 1st Battalion, Auckland Regiment on June 8.

Frank was wounded in the shoulder during the August Offensive and on 8 August 1915 boarded the HS Dongola bound for a hospital in Cairo. He was then transferred to Special Camp in Zeitoun on August 20 and did not rejoin his unit in Ismailia until 18 January 1916. On 6 April 1916 Frank Clark left Egypt on the Faconia bound for France.

Private Frank Clark was wounded for a second time at Armentieres on 24 June 1916 with a slight gunshot wound to his head but was fit enough to rejoin his unit on 8 July, and move with them down to the Somme. On 9 September F. Clark was bivouacked in fields on the edge of the battlefield at Fricourt Wood. On the morning of the 15 September, 1 Auckland moved to Mametz Wood and the next day the men marched to the battlefield and took over the line. Orders were given for an attack on Goose Alley, which were subsequently cancelled, so the Battalion dug the left defensive flank for the New Zealand Division. During this day F. Clark received gunshot wounds to his left thigh, which was serious enough to require evacuation to England. He was admitted to No. 1 NZGH, Brockenhurst on 24 September. He later died of these wounds. (Clare Church, New Zealand graves at Brockenhurst : 93 New Zealand soldiers remembered from World War One, 2002, p.42)